Inhibitor for chemical deterioration



Patented Mar. 23, 1943 L NE TED INHIBITOR FOB CHEMICAL DETEBJOEATION Herman L. Thwaltos, Clark Township, Union County, N. J., assignor, by mesne assignmen to Jasco, Louisiana ts, Incorporated, a corporation of.

No Drawing. Application November 30, 1939,

Serial No. 306,903

This invention relates to means for reducing the deterioration of unsaturated organic compounds and certain derivatives, and especially those com-' pounds which contain terminal methylene-type structures. It relates particularly to the incorporation in such compounds of materials in small amounts to reduce the tendency of relatively sim.. ple compounds to polymerize and to reduce the tendency of polymerized compounds to break down.

The present invention is based upon the fact that compounds containing olefinic linkages are usually chemically unstable at atmospheric temperatures, and especially in the presence of light at higher temperatures. This instability is evident in the simple olefinic compounds and in the polymerized unsaturated compounds containing olefinic structures. Hence the invention is concerned with the improvement in chemical stability of materials so widely different in physical properties as the liquid olefin hydrocarbons and the various commercial materials such as the vinyl, isobutylene and isoprene type resins, varnishes and coating compositions and even many type copolymer compositions. compounds having terminal methylene structures and their polymers and particularly such hydrocarbon compounds and their polymers and copolymers are stabilized by the compounds employed in the present invention. By the term, terminal methylene structure, is meant for the purposes of description in this invention the presence in the molecular structure of the unsaturated grouping, R1=CR2R3, in which R1 is the major portion of the molecule predominantly organic in character, preferably hydrocarbon or substituted hydrocarbon, and R2 and R3 are either hydrogen or short alkyl radicals, that is, radicals consisting of not more than three carbon atoms each. Increasing in these materials the resistance to deterioration by the additionof the stabilizing agents employed in this invention eliminates for all practical purposes the development of objectionable discoloration and odors in the compositions so prepared.

The nature of the changes which occur during the deterioration is obscure, but polymerization and depolymerization are evident effects. The re- In general, unsaturated The addition agents are compounds having an element of subgroup b of the fifth group of the periodic table excluding nitrogen combined directly to a carbon atom of at least one organic radical. Sub-group b of the fifth group of the periodic table excluding nitrogen contains phosphorus, arsenic, antimony and bismuth. These elements may be conveniently classed as the elements of the odd series of group V of the periodic table of atomic weights between 30 and 210. The term odd series" with reference to the periodic table covers those elements which occur in the odd numbered horizontal series of the periodic system of classification of the elements which starts with hydrogen. Combined with these elements, preferably in the trivalent state, are one or more organic radicals. These radicals may vary in character from having an aliphatic chain to cyclic, aikylated cyclic and heterocyclic structures and these may be substituted by the halide, hydrowl, mercapto, or amino groum. It is preferable that the compounds contain purely hydrocarbon monovalent radicals. It is of minor significance as to whether the groups are similar or in character, or whether one or two are replaced by hydrogen provided the compound itself is sufliciently oil soluble or can be readily dispersed in the materials to which they are added to bring about the desired effects. The radicals which have been found very satisfactory are the alkyl, aryl and alkyl-aryl groups.

The preferable' p compounds in the case of the derivatives of phosphorus and arsenic, are related in structure to phosphine and amne. Similarly, in the case of the derivatives of antimony and bismuth, the preferable type compounds are metallo-organics relate in structure to stibine and bismuthine. Examples of the preferred compounds have therefore, the general formula:

MRiRzR:

in which M may be phosphorus, arsenic, autimony or bismuth, and R1, R2, R3, may be organic radicals, preferably purely hydrocarbon, but one or two may be hydrogen.

The following examples illustrate the stabilizing activity of the compounds of the present invention when incorporated in simple compounds containing terminal methylene-type groups.

Examml room temperature. The light source was furnished by an 85 watt lamp (G. E.) type 3, and the samples were placed 14 cm. from the light source. The dishes were filled to a. depth of 3 mm. After the exposure the amount of polymer present was determined by the addition 01' three volumes of 95% ethyl alcohol. The styrene sample was almost entirely insoluble, while that containing 0.2% of triphenyl stibine was soluble except for the precipitation of triphenyl stibine asathinfllmonthesidesoithedish. The molecular weight oi. the polymer formed was estimated as being between 15,000 and 30,000.

Exam: 2

Four cc. (9.074 grams) quantities of styrene were taken. One was left lmblended and the others were blended respectively with triphenyl arslne, triphenyl stibine and triphenyl bismuthine in amounts of 0.2% by weight. The four samples were heated over a steam bath for four hours in the absence of light. On removing from the steam bath the samples were diluted with between 3 and 4 times their volume of 95% ethyl alcohol to precipitate the polymeric materials formed. The precipitates formed were washed several times with alcohol by kneading and the materials then dried. The polymers in each case had molecular weights of between 15,000 and 30,000. The amounts formed were as follows:

Weight e aht Sample polymerin g ggig m formed 1. Styrene (fresh distilled) 1.2 13. 3 2. Ditto-H). triphenyl-bismuthme 0.8 8. 9 3. Ditto+0. tnpheuyl-stibmeu 0.6 6.6 4. Ditto+0.2% triphenyl-arsme 0. 2 2 2 The eflect of the compounds upon the polymerization of isobutylene occurring in the presence of aluminum chloride is shown by the following data.

Exams 3 Aluminum chloride was dissolved in methyl chloride to give a solution and added to a flask. The solution was cooled to about -90 F. and isobutylene was bubbled into the solution until all reaction had apparently ceased. Similarly isobutylene was passed into methyl chloride solutions of 20% aluminum chloride to which were also added respectively 0.2% of triphenyl stibine, 0.2% triphenyl arsine and 0.2% triphenyl It is apparent from Examples 2 and 3 that the order of decreasing inhibitory eiiectiveness in terms of the non-or nic portion is arsenic, antimony and bismuth.

This example is presented to demonstrate again the controlling efiect of triphenyl stibine and triphenyl bismuthine upon the polymerization of compounds containing the methylene type structure. Isobutylene in this example was polymerized at l05 F. in the presence of boron fluoride as a catalyst. V

M Per cent w lht oi Inhibitor cone. Mm

formed None 0. 0 90, M l. 0 20, III) 0. l 30,0!) 0. 01 74, M 0. (D1 91, mo 1. 0 84, 0. l 01, m

Exam 5 carbons, moisture'or catalyst. This may be accomplished by milling or kneading at temperatures of 300-400 F. Polybutene materials, however, when milled at elevated temperatures for prolonged periods deteriorate forming compounds of lower molecular weight. This breakdown of polybutenes occurs during milling. .The deterioration may be inhibited by the addition of the inhibitors of this invention. In a test conducted with a 'mill employing two high pressure steam heated rollers of different 'diameter, revolving in opposite directions, polybutene materials with and without admixture with triphenyl stlbine were treated so as to give to the materials a. combined squeezing and shearing efiect at an elevated temperature. The following data were obtained:

Polybutene mol. wt.Xl03

7 tl'lpllelly l stibine mol. wt.Xl03

' Time, r lnutes Although it is usual to incorporate th inhibitors directly in the materials it is of advantage sometimes to dissolve the compounds in a suitable solvent and add in this manner either to incorporate in the mass or superficially to protect the surface.

Compositions in which the compounds may also be employed to advantage are the synthetic rubber-like materials formed by polymerization, as for example, of butadiene, or 2-chlorobutadiene, or by copolymerization, as for example, i

of styrene and certain diolefins, or even of butadiene and acrylonitrile. Copolymers which are obtained by reacting a low molecular weight olefin, preferably an iso-olefin, such as isobutylene, with low molecular weight diolefins, preferably a conjugated diolefin, such as butadiene. isoprene, dimethyl butadiene etc., may likewise be improved by treatment with the compounds of this invention. As such, these compounds of the invention are applicable to the prevention of age deterioration and flex-cracking of the copolym'ers of isoolefins and dioleflns having terminal methylene structures, such as, for ex- Polybutono ample, the copolymers formed by reacting isobutylene and butadiene at temperatures below 32 F. and preferably at temperatures between 110 F. and 150 F., or even as low as --180 F. in the presence of a suitable metal halide catalyst such as aluminum chloride dissolved in methyl or ethyl chloride. Any of these rubberlike compounds may or may not, be admixed with fillers; pigments, curing agents and the like.

'As many widely distinct embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that I do not limit myself to the specific embodiments therein.

I claim:

l. The process of inhibiting the polymerization and condensation of styrene which'comprises adding to styren a small amount of trip'henyl arsine. Y

2. A stabilized organic composition containing an organic compound having the vinyl group and a small amount of triphenyl arsine.

3. Styrene stabilized by the addition of a small amount of triphenyl arsine.

4. The process of inhibiting the polymerization and condensation ,of an organic compound having the vinyl group which comprises adding to said vinyl compound a small amount of a triphenyl compound of an element of the odd series of group V of the periodic table of atomic weight between 30 and 210.

5. A stabilized organic composition containing an organic compound having the vinyl group and a small amountof a triphenyl compound of an element of the odd series of group V of the periodic table of atomic weight between 30 and 210.

6. A-stabilized organic composition containing an organic compound having a vinyl group and a small amount of triphenyl stibine 7. A stabilized organic composition containing an organic compound having a vinyl group and a small amount of triphenyl bismuthine.

I HERMAN L. THWAITES. 

